A core basis of exercising is lifting a weight vertically against a force of gravity. These vertical motions, instead of horizontal or circular motions, are reproduced in fundamental exercises including the deadlift, the squat, and the bent row. Additionally, core biomechanical movements, such as walking and running, involve the feet, the arms, and the legs of a subject moving up and down in a vertical plane. Each step induces a vibration in the body that causes the muscles to contract or relax in order to sustain a balanced body position. These reflexes are involuntary and occur over a near instantaneous period of time, much like a knee jerk reaction.
As a result, performing body mass resistive exercises on a whole-body vibration (WBV) platform has become an increasingly popular training modality. Indeed, a visit at the local gym will demonstrate how popular vibration exercises currently are, with numerous devices available for exercise and physical therapy. Vibration is oscillatory motion about an equilibrium point, as illustrated in FIG. 7. Vibration is a mechanical oscillation, e.g. a periodic alteration of force, acceleration and displacement over time. Vibration exercise, in a physical sense, is a forced oscillation, where energy is transferred from an actuator (e.g. the vibration device) to a resonator (e.g. the human body, or parts of it). In many vibration exercise devices, these oscillations have sinusoidal shape, and they are therefore described by amplitude A, frequency f, and phase angle φ. As illustrated in FIG. 7, “A” denotes the mathematical amplitude, i.e. half the peak-to-peak displacement (D). The angular frequency ω is given as 2πf. During a vibration exercise, the human body is accelerated, which causes a reactive force by and within the human body.
The vertical oscillations generated via a ground based platform induce short and rapid changes in skeletal muscle fiber length (see, Marin et al., 2015, “The addition of synchronous whole-body vibration to battling rope exercise increases skeletal muscle activity,” J. Musculoskelet Neuronal Interact 15(3), 240-248; Cardinale, 2003, “The use of vibration as an exercise intervention,” Exerc Sport Sci Rev 31, 3-7; Hagbarth and Eklund, 1966, “Tonic vibration reflexes (TVR) in spasticity,” Brain Res 2:201-3; and Ritzmann et al., 2010, “EMG activity during whole body vibration: motion artifacts or stretch reflexes?,” Eur J Appl Physiol 110, 143-51, each of which is hereby incorporated by reference), which presumably stimulate reflexive muscle contractions increasing skeletal muscle activity. See, Ritzmann, Id., Abercromby et al., 2007, “Variation in neuromuscular responses during acute whole-body vibration exercise,” Med Sci Sports Exerc 39, 1642-50; Cardinale and Lim, 2003, “Electromyography activity of vastus lateralis muscle during whole-body vibrations of different frequencies,” J Strength Cond Res 17, 621-4; Hazell et al., 2007, “The effects of wholebody vibration on upper- and lower-body EMG during static and dynamic contractions,” Appl Physiol Nutr Metab 32:1156-63; Hazell et al., 2010, “Evaluation of muscle activity for loaded and unloaded dynamic squats during vertical whole-body vibration,” J Strength Cond Res 24, 1860-5; Marin et al., 2009, “Neuromuscular activity during whole-body vibration of different amplitudes and footwear conditions: implications for prescription of vibratory stimulation,” J Strength Cond Res 23:2311-6; Marin et al., 2012, “Acute effects of whole-body vibration on neuromuscular responses in older individuals: implications for prescription of vibratory stimulation,” J Strength Cond Res 26:232-9; Ritzmann et al., 2013, “The influence of vibration type, frequency, body position and additional load on the neuromuscular activity during whole body vibration, Eur J Appl Physiol 113, 1-11; Roelants et al., 2006, “Whole-body-vibration-induced increase in leg muscle activity during different squat exercises, J Strength Cond Res 20:124-9; Osawa and Oguma, 2013 “Effects of resistance training with whole-body vibration on muscle fitness in untrained adults,” Scand J Med Sci Sports 23, 84-95, each of which is hereby incorporated by reference.
The magnitude of these increases in skeletal muscle activity measured via electromyography (EMG) is dependent on the characteristics of the WBV stimulus (amplitude, size of each deflection) with higher frequencies and amplitude inducing greater muscle activity. See, Hazell et al., 2007, “The effects of wholebody vibration on upper- and lower-body EMG during static and dynamic contractions,” Appl Physiol Nutr Metab 32, 1156-63; Ritzmann et al., 2013, “The influence of vibration type, frequency, body position and additional load on the neuromuscular activity during whole body vibration,” Eur J Appl Physiol 113, 1-11; and Marin et al., 2012, “Whole-body vibration increases upper and lower body muscle activity in older adults: potential use of vibration accessories,” J Electromyogr Kinesiol 22:456-62, each of which is hereby incorporated by reference.
One design goal of existing exercise equipment has been to reproduce fundamental exercises on stable stationary platforms. To this end, existing exercise equipment has been designed with the goal of reproducing the naturally induced vibrations of the body. One approach for achieving this goal in existing exercise equipment has been to include a vibration mechanism attached in such equipment. However, such existing equipment, while successful in producing vibrations in an effort to reproduced the naturally induced vibrations of the body, has been unsatisfactory because there is no convenient way to turn on and off the vibrations. Once a user is on the device, it is inconvenient to have the user bend down and turn on the vibration source. Conversely, requiring a user to turn on the vibration source before getting onto the device causes the device, now turned on but without a user standing on the device, to jump around. Besides being inconvenient, this can be dangerous and can cause damage to other equipment that is typically in a gym, such as wall mounted mirrors.
As such, conventional equipment has also been unsatisfactory because it requires the exerciser to manually operate the vibration mechanism between exercise sets. Otherwise, the equipment will continue to vibrate when the user is unengaged with the equipment, moving and skittering across the ground. One solution for addressing such problems is to engineer such equipment so that it is very heavy, and thus will tend not to move and skitter when in vibrational operation without a user standing on the equipment. But this approach is unsatisfactory because it is difficult to move such equipment due to its excessive weight. Thus, advances in the design of such equipment is needed in order to increase stability and allow an exerciser to operate the device in a more convenient manner.
Given the above disclosure, what is needed in the art are improved vibrational exercise devices.